The present invention relates to a nebulizer-connecting device for respirators and generally for devices in which a user is supplied with breathing air via a delivery duct, for example a hose line.
In respirators, a patient who is to be respirated is supplied with breathing air via a hose line. In order to be able to add an aerosol to the breathing air, a nebulizer must be connected to the hose line in such a way that the aerosol generated by the nebulizer enters the breathing air delivered to the patient. As known from U.S. Pat. No. 4,951,661 or WO 02/089887, a nebulizer may be connected to the breathing-air duct by means of a T-fitting inserted in the hose line so that the aerosol flows through the tube section which discharges vertically into the tube section carrying the breathing air. In this way, the aerosol generated enters the breathing-air flow and is supplied via the delivery hose line together with the respiration air to the patient.
However, in clinical practice, for reasons of cost alone, nebulizers cannot be permanently connected, but have to be removed from the respiration air duct again when the aerosol therapy has been completed. The insertion and removal of the T-fitting with the nebulizer connected thereto is problematical since to do this it is necessary to interrupt the breathing air supply through the delivery duct from the respirator to the patient. Even if it is attempted to keep the interruption very brief, insertion and removal in this manner is not acceptable. Even without the separation of the respirator hose line, however, the attachment and removal of the nebulizer from the connecting fitting causes problems, since for a short time the T-fitting on the vertically extending connecting fitting is open, which impairs the patient's respiration. In addition, this method does not ensure that the connecting fitting is sealed again after the removal of the nebulizer, for example with a stopper. Some of these problems are also addressed in U.S. Pat. No. 4,951,661 or WO 02/089887.
Known from U.S. Pat. No. 4,951,661 is a T-fitting with a valve which seals the T-connector when no nebulizer is connected; in the sealed position, the valve element is secured by the action of a spring. Connecting a nebulizer to the T-connector causes the valve element to be lifted against the action of the spring. The T-fitting design known from U.S. Pat. No. 4,951,661 is unfavourable for several reasons. The valve element's spring is arranged in the aerosol's flow path and thus impedes the supply of the aerosol. In addition, the spring becomes contaminated and is difficult to clean. The lifting of the valve element is performed by means of a punch which is also located in the flow path of the aerosol and disrupts the flow. In addition, the lifted valve element is arranged in the breathing-air flow and hence also impedes the flow here as well.
In order to rectify some of the errors in the design known from U.S. Pat. No. 4,951,661, WO 02/089887 proposes that the spring for the valve element is not arranged centrally in the T-connector around the punch shaft but in a housing arranged around the wall of the T-connector. This ensures that the spring is arranged in an enclosed space and hence cannot become contaminated. However, the design known from WO 02/089887 is still unfavourable since once again the punch, the punch shaft and the valve element are arranged so that they impede the flow thus causing aerosol losses since the aerosol is readily precipitated on the numerous surfaces arranged in the flow path. The spring housing causes the T-connector to be narrowed. In addition, in lifted condition, the valve element is in the flow path of the breathing air.
It should be noted with regard to both constructions that due to the spring, which has an indispensable restoring force in order to prevent the T-fitting remaining open after the removal of the nebulizer, both designs are very complicated and present problems with regard to cleaning and sterilisation.